1. Technical Field
This disclosure relates generally to an elevator and, more particularly, to a belt drive for opening and closing an elevator door.
2. Background Information
An elevator car typically includes a drive for opening and closing an elevator door. In some cases, the drive may be a belt drive, wherein a belt having a plurality of protrusions (e.g., cogs or teeth) arranged along its length is wrapped around a plurality of sheaves. The belt protrusions mesh with corresponding protrusions on the sheaves, preventing the belt from slipping relative to the sheaves. The meshing between the protrusions, however, may generate undesirable noise.
Alternatively, friction belt drives may be used to drive elevator doors. Such friction belt drives use belts, for example v-belts, that are wrapped around a plurality of sheaves. Neither the belt nor the sheaves of such drives include protrusions, but instead rely on the friction between the belt and the sheaves to provide a motive force. Friction belt drives may therefore generate less noise than cogged belt drives. However, it is often difficult to precisely control friction belt drives because the belts may slip relative to one or more of the sheaves during operation. Such slippage may be at least partially accounted for by monitoring the position of the elevator door, or the angular position of one of the sheaves. However, systems for monitoring the position of the elevator door and/or the angular position of one of the sheaves may be complicated, expensive, and/or inaccurate.
There is a need in the art for an improved belt drive for opening and closing an elevator door.